Spatial Modelling of Common Chimpanzees’ (Pan troglodytes schweinifurthii) Ecological Niche in the Western Part of Rwanda

The Western Part of Rwanda is a mountainous region that hosts two important forest parks namely the Nyungwe National Park (NNP) and Gishwati-Mukura National Park (GMNP). The two parks which are located in the Albertine Rift region are known for their high endemism and harbour several endangered plant and animal species, including particularly the Common Chimpanzees (Pan troglodytes schweinifurthii). However, these forests are facing threats including mainly habitat loss, aggravated by climate change both of which are continuously having direct and indirect effects to the Chimpanzees. While conservation of chimpanzees appears critical, there is a need to deeply understand the dynamics of their habitat. This study aimed at modelling the ecological niche of common chimpanzee by integrating species distribution data and environmental layers. Species location data collected in both NNP and GMNP were integrated with environmental variables (temperature, precipitation, altitude, and land cover) through Maximum Entropy (MaxEnt), and Generic Algorithm for Rule-based Prediction (GARP) Models. The results of both models showed that chimpanzees prefer the Southern and the Northern parts of the study area (0.5 < p < 0.87), which is characterised by high altitude, low temperature, and intensive rainfall. It was also noted that MaxEnt predictions were more accurate compared to the GARP’s. MaxEnt predictions showed that 35% (2058.61 ha) of the Western Province are suitable for chimpanzees, while GARP predicted that only 24% (1411.62 ha) are suitable. Furthermore, the study found that the high precipitation, annual and maximum precipitations, and food availability are the most determinants of chimpanzees' habitat. The land use in the Western Province has made the central part less suitable to chimpanzees and therefore, this study recommends that special efforts for the conservation of Common chimpanzees in Rwanda should be concentrated in the Southern Part (around NNP) Nyungwe National Park (main forest and Cyamudongo fragment) and the northern Part (around GMNP) Keywords: Spatial Modelling, Common Chimpanzee, Ecological Niche, Nyungwe National Park, Gishwati-Mukura National Park, Rwanda.

Complete Genome Sequence of a Novel Chimpanzee Polyomavirus from a Western Common Chimpanzee

We report here the full-length genome sequence of a novel chimpanzee polyomavirus. Viral sequences were recovered from colon, bladder, and ureter tissue from a western common chimpanzee. The virus is genetically closely related to the human BK polyomavirus.

Unconstrained cranial evolution in Neandertals and modern humans compared to common chimpanzees

A variety of lines of evidence support the idea that neutral evolutionary processes (genetic drift, mutation) have been important in generating cranial differences between Neandertals and modern humans. But how do Neandertals and modern humans compare with other species? And how do these comparisons illuminate the evolutionary processes underlying cranial diversification? To address these questions, we used 27 standard cranial measurements collected on 2524 recent modern humans, 20 Neandertals and 237 common chimpanzees to estimate split times between Neandertals and modern humans, and between Pan troglodytes verus and two other subspecies of common chimpanzee. Consistent with a neutral divergence, the Neandertal versus modern human split-time estimates based on cranial measurements are similar to those based on DNA sequences. By contrast, the common chimpanzee cranial estimates are much lower than DNA-sequence estimates. Apparently, cranial evolution has been unconstrained in Neandertals and modern humans compared with common chimpanzees. Based on these and additional analyses, it appears that cranial differentiation in common chimpanzees has been restricted by stabilizing natural selection. Alternatively, this restriction could be due to genetic and/or developmental constraints on the amount of within-group variance (relative to effective population size) available for genetic drift to act on.

A Guttman-Based Approach to Identifying Cumulativeness Applied to Chimpanzee Culture

Human culture appears to build on itself—that is, to be to some extent cumulative. Whether this property is shared by culture in the common chimpanzee is controversial. The question previously has been approached, qualitatively (and inconclusively), by debating whether any chimpanzee culture traits have resulted from individuals building on one another’s work (“ratcheting”). The fact that the chimpanzees at different sites have distinctive repertoires of traits affords a different avenue of approach: determining whether the traits accumulate, site to site, in a structure more orderly than would be expected by chance. Here we use Guttman scalograms and a gamma-type statistic to bring the first quantitative evidence to bear on the question. We show that while traditional methods provide apparent support for a cumulative tendency, our more rigorous methods do not. This may be because cumulativeness requires human-like social-learning mechanisms, or because culture generally is not sufficiently unidimensional to scale well. A cumulative tendency would be expected, however, under rather weak assumptions; therefore it seems more likely that chimpanzee culture is cumulative, but this data set is simply too small to evidence it.